O
/
REMARKS
AND
E X P E R I M E N T S
ON DIFFERENT PARTS
OF THE
PROCESS OF BREWING;
ON THE CONTINUED APPLICATION
OF A
BOILING HEAT
DURING THE
OPERATION OF MASHING.
OXFORD,
Printed by Nathaniel Bliss,
FOR R. BLISS, AND R. BLISS, JUN.
AND SOLD BY F. AND C. RIVINGTONJ CADELL AND DAVIES;
w. MIILAR; LONGMAN, HURST, REES, & ORME;
VERNOR, HOOD, & SHARPE ; J. HARDING J
AND MESSRS. RICHARDSONS, LONDON,
1807.
LOAN STACK
-'..
TP570
TO THE READER.
SO many Treatises on Brewing have been
already published, and some of these enter
so minutely into the detail of the process,
that it would be superfluous to add to their
number except with the hope of adding
also to the information they contain : whe-
ther the remarks and statements made in
the following pages are to be considered
as of any interest, beyond what degree of
novelty may belong to them, is left to the
judgment of those who have more experi-
ence than the Author ; and who can there-
fore better form an opinion whether they
are likely to lead to any practical improve-
ment : the hope that they may possibly lead
to such an end is the best apology for pub-
lishing them.
447
REMARKS,
THE .principal and only essentially neces-
sary substances employed in the composi-
tion of Beer, or Malt Liquor in general, are
water, malt, and hops: and the ultimate
object of the Brewer is to combine with the
water as much as possible of the saccharine
and other soluble matter of the malt, toge-
ther with the bitter and aromatic particles
of the hops. Hot water effects this pur-
pose more speedily, and to a greater ex-
tent, than cold ; and, when thus impreg-
nated with the soluble matter of the malt
and hops, constitutes what is called Wort :
in which the saccharine matter, principally,
renders the mixture capable of fermenta-
tion ; the bitter and aromatic particles pre-
vent that fermentation from proceeding too
far,
B
The process of Brewing is commonly
conducted nearly in the following manner :
in describing which a reference is princi-
pally made to the brewing of table beer
from fresh malt ; that is, from malt which
has not been already used for brewing ale.
The quantity to be brewed may be taken
as a barrel, or thirty-six gallons, from two
bushels and a half of malt ; and the di-
mensions of the vessels, &c. may be sup-
posed to correspond with those used in a
moderate family ; the copper, for instance,
holding thirty gallons.
A quantity of boiling water being poured
into a vessel, called a Mash-Tun, is suf-
fered to remain there till it has cooled to
a temperature rarely if ever exceeding 180
of Fahr! : the malt, previously broken in
a mill so that each grain shall have been
divided into two or three parts, is then
thrown into the water ; and, by means of
an instrument called an Oar, is stirred about
in, and thoroughly mixed with it : this me-
chanical agitation of the malt and water,
technically called Mashing, is kept up for
about a quarter of an hour ; by which the
malt is more effectually brought into contact
with the water, and a greater proportion of
its soluble matter extracted. After this the
mash-tun is covered over, in order to retain
as much heat as possible, and the whole is
suffered to remain undisturbed for an hour
and half, or two hours. At the end of that
time, the water thus impregnated with the
extracted particles of the malt (in which
state it is sometimes called Sweet-Wort,
sometimes simply Wort,) is drawn off into
another vessel. The quantity of water used
in this first mashing is about twenty-five
gallons ; of which not above fifteen are ob-
tained, the rest being absorbed by the malt,
with the exception of a small quantity car-
ried off by evaporation.
This first wort being drawn off from the
malt, a fresh portion of hot water is thrown
into the mash-tun, at a temperature vary-
ing, according to the judgment of the
brewer, from 180 to 212 of FahrJ: the
process of mashing is repeated during the
space of ten minutes ; and, the tun being
again covered, the whole is suffered to re-
main for about an hour ; at the end of
which time a second wort is drawn off.
The quantity of water used in this second
mashing is about fifteen gallons ; and, the
malt having already retained as much wa-
ter as is sufficient to saturate it, the whole
amount of the fifteen gallons is afterwards
recovered from the mash-tun.
A fresh quantity of hot water, about
twelve gallons, is now added to the malt ;
and the mixture, being mashed for a few
minutes, is suffered to remain in the tun for
half an hour, or an hour, or more, in order
to form a third wort.
In the mean time a part of the two first
worts is poured into the copper, with a pound
and half or two pounds of hops, and boiled
for an hour, or an hour and half: after
which it is strained through a sieve into
another vessel. The third wort is now
drawn off from the mash-tun ; and, being
mixed with the remaining part of the first
and second, is boiled, for an hour or more>
with the hops used in the former instance.
The three worts are then distributed intQ
shallow vessels, called Coolers, and suffered
to remain there till they have nearly sunk
to the temperature at which it may be
thought right to promote fermentation:
they are then collected into one vessel,
Called a Fermenting Vat ; and, by the ad-
dition of about a quart of yeast, that pro-
cess is soon produced, which converts the
wort into beer.
THIS short description of the common
method of brewing table beer will be suffi-
cient for the purpose of introducing the fol-
lowing remarks, which have a reference to
particular parts of that process ; and, in-
deed, of the process of brewing in general.
With respect then to the water employed
in brewing, that which is soft is by many
recommended in preference to that which
is hard ; and as the solvent power of wa-
ter, as well as its softness, is generally in
proportion to the degree of its purity, there
would be reason for that preference were
extreme accuracy required ; but, when we
consider that hard water scarcely ever holds
in solution more than what would amount to
one thousandth part of its weight, and that
10
in many cases a great proportion of this is
deposited during boiling ; and, when we
again consider that the wort even from
which the strongest ale is to be produced
might be still further impregnated with the
soluble matter of the malt and hops, there
does not appear any reasonable ground for
the preference ; or, if there is, it does not
hold good in practice. The just preference
which is given to soft water in another eco-
nomical process, namely Washing, affords
indeed a plausible ground for a preference
in this also : but the objections to the use
of hard water rest really on very different
grounds in the different cases, as they who
are at all acquainted with the principles of
chemistry well know : it may be sufficient
for the present to observe, that in the case
of brewing the force of the objection is les-
sened in proportion as the quantity of wa-
ter is increased ; while in the case of wash-
ing the force of the objection is increased
in proportion to the increase in the quan-
tity of the water.
It may be considered therefore as of very
little consequence whether rain, or river, or
11
spring water be employed ; nor is it of more
consequence whether, in the process of
mashing, the hot water is taken before 01
after boiling, provided it is of that tempera-
ture which may be determined on as fit for
the process. The direction therefore com-
monly given of pouring the boiling water
into the mash-tun, there to remain till the
steam rises in so small a quantity that a
person may see his face in the water below,
is only an empirical mode of ascertaining
that the temperature is now proper for the
addition of the malt, without, as it is tech-
nically called, " setting the goods :" the
meaning of which term may perhaps be un-
derstood from the following explanation.
Water at or near the boiling point very
readily converts any farinaceous substance,
like malt, into a paste ; arid this paste is im-
pervious, or nearly so, to liquids in general :
but, as it is the object of mashing to give
the water an opportunity of dissolving the
saccharine particles of the malt, the effect
must necessarily be in a great measure pre-
vented, if the surface of each particle of the
malt, by being converted into a paste, pre-
12
vents the water from penetrating into the
body of it : the common language there^
fore on this occasion is very expressive,
which says, that the too great heat of the
water closes the pores of the malt.
In the process of brewing, as already de-
scribed, it is seen that the first wort being
withdrawn from the malt, a second and a
third are obtained : and the reason of mash-
ing with three separate portions of water
instead of with the whole quantity at once,
is partly because, in the latter case, a great
portion of a richer wort would be retained
by the grains (so the mass is called which
remains in the mash-tun after all the wort
has been drawn off from it), which now is
more completely washed out by the re-
peated addition of fresh water ; and partly
because the water itself in divided quanti-
ties extracts more abundantly the soluble
parts of the malt, than the same quantity
of water used at once would be able to do.
THE process of mashing, if conducted
properly, is supposed to extract as much of
the soluble matter of the malt as can be
extracted with economy : in the subsequent
process of boiling the wort with the hops
two ends are answered; for at the same
time that the bitter and preservative qua-
lity of the hops is united with the wort, the
wort itself is increased in strength : that is,
its bulk being reduced by evaporation,
which merely carries off the watery parti-
cles, the original quantity of saccharine
matter &c. remains, diffused through a
smaller space than it was before.
The distribution of the wort into coolers,
after it has been boiled with the hops, is
evidently for the purpose of lowering its
temperature as quickly as possible; and
this is done not only to save time, but also
to prevent its growing sour, which other-
wise, especially in warm weather, would
often happen. For the same reasons also
yeast is added ; the process of fermentation
not absolutely depending on, but being
very materially accelerated by the addition
of, that substance.
With respect to the nature of fermenta-
c
14
tion itself, such observations as have oo
curred in the course of the Experiments
hereafter described will be mentioned in the
latter part of this Treatise.
THE foregoing account is, in a general
view, applicable to the common method of
brewing malt liquor ; in referring to which
it appears, that the reason of the different
parts of the process is easily deducible from
a slight consideration of the joint properties
of water and heat. Since therefore it is
evident that, in mashing, Hot water is vised
in preference to Cold, because it more
pov/erfully and in a shorter time extracts
the soluble part of the malt ; and, that the
reason for limiting the degree of heat is
only to prevent the malt from being con-
verted into a paste, which in a great mea-
sure w r ould exclude the water from acting
upon it; it appears fair in reasoning to
suppose, that, if an increased heat could be
applied without producing that effect, the
soluble part of the malt would be still more
abundantly, or at least more quickly, ex-
tracted : and it was the hope of answering
15
this end which in the present instance led
to. the experiment of gradually heating the
malt and water together to the boiling
point. For, as every intermediate degree
of heat, between the common temperature
and that usually employed in mashing,
would extract some of the soluble matter
of the malt, it appeared probable that
each particle would be so far softened and
loosened in its texture, by the time it had
reached this heat, that an increase of tem-
perature would not have the effect which it
has when applied at once to the cold and
unsoftened malt : and this reasoning is sup-
ported in some measure by practice ; for
after the first mashing the rule of not ap-
plying water above a certain temperature is
very frequently disregarded.
This inference appears so obvious, that,
although it is not taken notice of in any
of the publications on the subject of brew-
ing, it very probably has occurred to many
persons ; and the practice to which it leads
has, perhaps, not been adopted because in
opposition to general opinion. However this
16
may be, the experiment has fully succeeded
in as many as twenty instances ; and, at the
3ame time that this method of brewing pro-
duces a kind of beer altogether not inferior
to that obtained by the common method,
from similar proportions of malt and hops,
it possesses the additional advantage of be-
ing attended with some less trouble and loss
of time, and perhaps some less expense.
It now remains therefore to give an ac-
count of the Experiments that were made
for the purpose of proving the truth of
the foregoing reasoning, accompanied with
such remarks as seem applicable to the se-
veral results.
IN public breweries the intrinsic value
of the wort, with respect to its saccharine
contents &c., is estimated by means of an
hydrometer ; which, by shewing the differ-
ence in specific gravity between the wort
and simple water, gives the means of calcu-
lating the absolute weight of saccharine
matter, &c. contained in an} 7 given quan-
tity of the former.
17
An instrument of this kind was tried in
the present experiments ; but, owing to
some fault either in itself or in the con-
struction of the table of calculations which
accompanied it, it was not found sufficient-
ly accurate ; and therefore it was thought
better to make a calculation of the propor-
tion of soluble matter extracted from a
given quantity of malt and hops by taking
the absolute weight of a given quantity of
wort made from them. This, though not so
scientific a method as the other, has, from
the nature of the apparatus, the advantage
of being less liable to error.
For this purpose a glass vessel was em-
ployed (having a narrow cylindrical neck),
which when perfectly dry weighed 1844 gr s .
The balance by which this vessel was weighed
would easily turn with half a grain when
4000 grains were in each scale ; and a fine
line being drawn with a diamond round the
cylindrical part, it might easily be filled
with water to that mark several times
itf succession, without the variation of a
grain in the weight of the contents.
That quantity of distilled water, Gr.
at 55 of FahrS weighed v . . 2600
The same quantity of water of the
river Isis, at Oxford, weighed so
nearly the same at the same tem-
perature, that the difference could
not be satisfactorily estimated.
The same quantity of pump-water of
Oxford, at the same temperature,
. weighed 2602
but after having been boiled for
ten minutes, .and then reduced
to the original, .temperature, it
weighed 2600.5
The difference in the weight, between the
fresh and the boiled water, is owing to the
deposition of that earthy matter by which
the inner surfaces of vessels, used for boiling
such water, are said to be furred ; and
as in this state its weight is to that of dis-
tilled water as 2600 to 2600.5, the differ-
ence is no more than -^- O th part ; which is
too small to deserve notice.
19
In weighing then the above quantity of a
given wort it is clear that whatever was the
excess above 2600 grains was due to a part
of the soluble matter that had been extracted
from the malt and hops, with the difference
already stated of ^th part ; and then the
proportion in any other quantity of the
same wort was easily found by calculation
from the following data.
The cubic contents of an Eng- Cub. Inch 3 .
lisli wine pint are 28.875
And the weight of an English
wine pint of distilled water, Gr s .
at 55 of Fahr?, is ... 7310.428125
The cubic contents of an Eng- Cub. inch 5 .
lish beer pint are 35.5
And the weight consequently, Gr.
at 55 of Fahr!, is .... 8924.41875
But, since 2600:1 :: 8924.41875:3.43246,
it appears that for every grain which this
quantity of a given wort weighed above
2600 grains there is to be allowed as the
20
proportional increase
Gt\
In a pint of the same wort . . , 3.43246
In a gallon 27.45968
And in a barrel (36 gallons) . 988.54848
From these data the following table
was constructed : in which the column on
the left hand marks the difference in weight
between a quantity of water weighing 2600
grains, and the same quantity of a given
wort ; the columns on the right hand shew
the proportional increase in the gallon and
barrel. That increase, multiplied by the
number of gallons or barrels of wort ob-
tained, shews the absolute weight of the
soluble matter extracted from any given
quantity of malt and hops ; which is all
the brewer desires to learn from the use
of the common hydrometer, the place of
which instrument was in the following ex-
periments supplied by the apparatus alrea-
dy described.
TABLE
OF THE
tVeight of Saccharine Matter, fyc. in a GALLON and BARREL
of a given Wort, according to the Difference in Weight be-
tween a Quantity of Water weighing 2600 gr s . 5 and the
same Quantify of that Wort.
Increase in
Weight of the
given quantity
of WORT by
Grains.
Proportional Increase
in the GALLON and BAUREL,
calculated
by Avoird. Weight.
GALLON. BAHREL.
Gr'.
Ib.
Oz.
Gr'.
ib.
Oz.
Grs.
1 .
27.45
2
113.54
2 .
54.90
4
227-08
3 .
82.35
6
340.62
4 .
109.80
9
16.66
5 .
137.25
11
130.20
6 .
164.70
13
243.74
7 .
192.15
15
357-28
8 .
219.60
1
2
33.32
9 .
247.05
1
4
146.86
10 .
274.50
1
6
260.40
20 .
1
111.50
2
13
83.30
30 .
1
385.00
4
3
343.70
40 .
2
223.00
5
10
166.60
50 .
3
59.00
7
427.00
60 .
3
334.50
8
7
249.90
70 .
4
170.50
9
14
72.80
80 .
5
6.50
11
4
333.20
90 .
5
282.00
12
11
156.10
100 .
6
118.00
14
1
416.00
00 .
o
12
236.00
28
3
394.50
Iii order to prevent a troublesome repe-
tition of words, it may be convenient here
to observe, that, in conducting the follow-
ing Experiments, the specific gravity of
each wort was taken at the temperature
of between 55 and 60 of Fahr* ; and the
quantity was calculated at the same tem-
perature : for convenience also the speci-
fic gravity of each wort will be signified
by a reference to the numbers in the left
hand column of the foregoing table. Thus,
if the sp. gr. of a wort is said to be 100, it
is to be understood that a quantity of that
wort equal in bulk to a quantity of wa-
ter weighing 2600 gr s . exceeded the weight
of that water by 100 gr s .; which is in the
proportion of 6oz. 118gr 8 . to the gallon,
and 14lb. loz. 412.5gr s . to the barrel.
EXP*. i.
Sixteen gallons of river-water, together
with a pound of hops, and i. of a bushel of
malt ground smaller than usual, were put
into a copper, the capacity of which was
twenty gallons: the whole was gradually
heated till it boiled, and after it had re-
mained at the boiling point for half an hour
it was strained through a hair sieve.
The sp. gr. of this wort was
164. The quantity of it
was 8 gallons. It therefore
contained of saccharine mat- Ib - oz - rs -
ter, &c 5 2 123
The malt and hops w r ere returned into
the copper: fourteen gallons of water being
then added to them, the whole was made
to boil ; and immediately after boiling was
strained.
The sp. gr. of this wort was
50. The quantity of it was
12 gallons. It therefore con-
tained of saccharine matter, lb - oz - "
&c 2 5 270
The malt and hops were now
boiled a third time, and gave
6 gallons of a wort, the sp.
gr. of which was 24 : that
quantity contained therefore
&c. 9 15
The process was again repeated,
and produced 6 gallons of
a wort, the sp. gr. of which
was 12 : the 6 gallons there- Ib - <*. grs,
fore contained &c, , , , 4 225
Thus the whole weight of soluble
matter extracted was . . . 8 5 196
and the quantity used being
| of a bushel, the proportion
in the quarter, or 8 bushels, is 75 1 14
The first and second worts being mixed
together at the temp, of 82 of Fahr 1 ., a pint
of yeast was added to them, and they were
immediately put into an 18 gallon barrel.
The fermentation of the liquor proceed-,
ed in the usual way for several days ; and
the beer produced was at the end of three
weeks tolerably transparent, and of a good
taste.
EXP'. 11,
Fifteen gallons of pump-water were gra^
dually heated to the boiling point, with 9
pf a bushel of malt ground down nearly tq
the state of flour; and the mixture was
kept at the boiling heat during an hour and
a half.
The sp. gr. of the first wort was
164. The quantity of it was
9 gallons. It contained there- Ib - 02. grs.
fore of saccharine matter, &c. 512 48
The malt was again boiled with a fresh
portion of water for an hour and a half.
The sp. gr. of the second wort
was 72. The quantity of it
was 9 gallons. It therefore lb - oz - g rs
contained c 2 8 278
The sum of the soluble contents
of the two worts is ... 8 5 89
And the quantity of malt used
being of a bushel, the
proportion in the quarter, or
8 bushels, is 74 14 359
The two worts being mixed, and the
sp. gr. of the mixture taken, which was
118, they were boiled for three quarters of
an hour with a pound of hops : enough
boiling water was added to make up the
quantity lost by evaporation, and the sp. gr.
was again taken : it was now 118.5.
A part of this wort, mixed at the temp,
of 88 with a pint of yeast, was poured
immediately into a fifteen-gallon barrel.
Fermentation proceeded in the usual man-
ner, and at the end of the third day the
sp. gr. of this beer was 44.
At the end of the eighteenth day the sp. gr.
was 34.
On the twenty-fourth day the sp. gr. was
only 29 : the beer was very transparent,
dark coloured, and of a good taste.
EXP*. ui.
Fifteen gallons of river-water were boiled
for four hours with a pound of hops and
of a bushel of malt, as finely ground as in
the last Exp'.
The sp. gr. of the first wort was
200. The quantity of it was
6 gallons. It contained there- ib. oz. grs.
fore &c 4 11 103
The malt and hops were again boiled with
pump-water for two hours.
The sp. gr. of the second wort
was 103. The quantity was
7 gallons. It contained there- lb - oz - rs -
fore&c 2 13 90
Four gallons of cold water were now
poured upon the malt and hops ; arid hav-
ing been mashed with them for ten minutes
were immediately strained off.
The sp. gr. of this third wort
was 67. The quantity was 4
gallons. It contained there- lb - oz - grs *
fore &c. 1 356
28
The quantity extracted from $
of a bushel of malt in this lb - z - s rs '
instance amounted to . . 8 9111
The proportion therefore in the
quarter, or 8 bushels, is . 77 3 124
The sp. gr. of the three worts mixed toge-
ther was 129. A pint of yeast was added to
the mixture * which at the temp, of 82 was
poured into a fifteen-gallon barrel. Fer-
mentation proceeded moderately; and on
the twentieth day the sp. gr. was 35.
EXP I . iv.
Sixteen gallons of pump-water were boil-
ed for an hour and half with a pound of
hops and-^ of a bushel of malt, finely ground ;
and the mixture was constantly stirred toge-
ther during the whole of the time.
The sp. gr. of the first wort was
150. The quantity was 9 gal-
lons. It contained therefore Ib> oz - s rs -
5 4 280
The malt and hops were again boiled and
stirred together during two hours.
The sp. gr. of the second wort was
65. The quantity was 9 gal-
lons. It contained therefore lb - oz. grs.
&c 2 4 308
The sum of the soluble contents
of the two worts is . . . 7 9 151
And the quantity of malt used
being -| of a bushel, the
proportion in the quarter, or
8 bushels, is ..... 68 4 46
The sp. gr. of the mixture of the two
worts was 108; to which at the temp, of
80 a pint of yeast being added, the fer-
mentation was carried on in an open tub :
and at the end of ten hours the beer was
put into a fifteen-gallon barrel : at the end of
sixty hours from the addition of the yeast
the sp. gr. was 40.
30
EXP*. v.
Fifteen gallons of pump-water were boil-
ed with i of a bushel of malt finely ground,
and three quarters of a pound of hops, for
two hours ; and the mixture was constantly
stirred during the w^hole of the time.
The sp. gr. of the first wort was
160. The quantity of it was 6
gallons. It contained there- lb - < s rs -
fore&c. . 3 12 90
The malt and hops were again boiled &c.
with fresh water for two hours.
The sp. gr. of the second wort
was 100. The quantity was
10 gallons. It contained lb - oz - s rs -
therefore &c 3 14 305
The quantity extracted from i
of a bushel in this instance lb - oz - s rs -
weighed 7 10 395
31
The proportion therefore in the ib. z- g-
quarter, or 8 bushels, is . . 69 2 55
EXP'. vi.
Sixteen gallons of river-water were boiled
for two hours with a pound of hops and
- of a bushel of malt, ground in the
common manner, and the mixture was con-
stantly stirred during the whole of the
time.
b
The sp. gr. of the first wort was
148. The quantity was 8
gallons. It contained there~ lb - oz - s rs>
fore&c 4 10 109
The malt and hops were again boiled
&c. with a fresh portion of water for two
hours.
The sp. gr. of the second wort
was 65. The quantity was 7
gallons. It contained there- lb - oz .* s rt$ -
fore &c 1 12 239
32
The quantity extracted in this
instance from 9- of a bushel lb - oz - s rs -
of malt weighed .... 6 6 349
The proportion therefore in the
quarter, or 8 bushels, is . 57 13 78
Exp 1 . VIT.
Fifteen gallons of water were boiled for
three hours, and stirred at the same time,A\dth
o
- 9 - of a bushel of malt ground in the usual
manner: six gallons of cold water were then
added and the whole was made to boil &c.
for two hours. Six gallons of wort were then
strained off, and nine gallons of cold water
were added to the malt and hops : these
were mashed together for half an hour,
and then strained into the former six gal-
lons.
The sp. gr. of this wort was 98.
The quantity thus obtained
was 16 gallons. It contained lb - oz - s rs -
therefore &c. .62 150
33
And this being the quantity ex-
tracted from -- of a bushel,
the proportion in the quarter, i b - oz. grs.
or 8 bushels, is .... 55 5 37
A pint of yeast was added to these six-
teen gallons, at the temp, of 78, in an
open tub; and at the end of twenty-four
hours the beer was put into a fifteen-gallon
barrel. At the end of seventeen days its sp.
gr. was 43, and it was tolerably transparent.
EXP*. vin.
Fifteen gallons of water were boiled, and
constantly stirred for an hour, with 9 - of a
bushel of malt, ground in the common man-
ner, and three quarters of a pound of hops.
The whole was then thrown into a mash-tun,
and six gallons of wort were drawn off and
returned into the copper: ten gallons of
cold water were then added to the malt and
hops, and being mashed with them for
ten minutes were drawn off and added to
the six gallons in the copper: these sixteen
34
gallons were made to boil, and in the mean
time seven gallons of cold water were added
to the malt and hops and mashed with them
for an hour ; after which they were drawn
off and added to the quantity contained in
the copper ; which was made to boil during
three hours and a half.
The sp. gr. of this wort was 110.
The quantity was 151 gallons. lb - oz - rs -
It therefore contained &c. . 6 10 396
which being the quantity ex-
tracted from ^ of a bushel,
the proportion in the quarter,
or 8 bushels, is 60 2 64
A pint of yeast was added to this wort
at the temp, of 88, the temp, of the sur-
rounding atmosphere being 52 ; and three
hours afterwards fermentation was going on
very favourably. This beer was put into
a barrel twenty-four hours after the addi-
tion of the yeast : at the end of ten days it
was very transparent, and of a good taste ;
and its sp. gr. was 50 : at the end of eigh-
teen days its sp. gr. was 43.
35
EXP'. ix.
Fifteen gallons of water were boiled and
constantly stirred for an hour and half,
with -5 of a bushel of malt ground in the
common manner, and three quarters of a
pound of hops : the whole was then thrown
into a mash-tun, and the wort was drawn
off.
The sp. gr. of this wort was 152.
The quantity was 9 gallons. lb - oz - g-
It contained therefore &c. . 5 5 337
This wort being returned into the copper,
a fresh quantity of cold water was mashed
with the malt and hops for about ten mi-
nutes : a second wort consisting of nine gal-
lons was then drawn off, and added to that
in the copper : in the same manner a third
wort was obtained amounting to three gal-
lons, which was added to the two first worts;
and the \thole was boiled together for two
hours.
The sp. gr. of the wort thus ob-
tained was 108. The quan-
tity of it was 15 gallons. It lb - oz. g rs -
contained therefore &c. ..65 251
which being the quantity
extracted from -^ of a bushel,
the proportion in the quar-
ter, or 8 bushels, is ... 57 2 71
A pint of yeast was added to this wort
at the temp, of 90 ; and within two hours
it was fermenting rapidly and favourably :
the temp, of the surrounding air at the same
time was 40. Fermentation proceeded in
the usual manner and at the end of ten
days the sp. gr. of this beer was 48 ; and it
was as transparent as beer is usually.
EXP*. x.
Fifty gallons of pump-water were boiled
&c. for an hour, with four bushels of malt
ground in the common manner, and three
pounds of hops.
37
The sp. gr. of the first wort was
188. The quantity was 26
gallons. It contained there- lb - oz. grs,
fore &c 19 2 195
Thirty-six gallons of cold water were now
added to the malt and hops in the copper,
and the whole was made to boil &c., and
then strained off.
The sp. gr. of the second wort
was 86. The quantity was
36 gallons. It contained H>. oz. grs.
therefore &c 12 2 38
Six gallons of cold water were thrown on
the malt and hops in the copper ; the whole
was mashed together for ten minutes, and
a third wort was then drawn off.
The sp. gr. of this third wort
was 30. The quantity was 9
gallons. It contained there- ib. oz. grs.
fore &c 10 402
The quantity extracted in this
instance from four bushels
weighed 32 5 197
38
The proportion therefore in the Ib - oz - e-
quarter, or 8 bushels, is . . 64 10 394
The sp. gr. of the mixture of the three
worts was 115; three pints of yeast were
added to it at the temp, of 95, the temp.
of the surrounding air being 60. During
fermentation there was a very violent effer-
vescence in the liquor, but the bubbles,
which rose in great numbers, were not ac-
companied with that white tenacious froth
which is generally present ; and the temp.
of the liquor remained sensibly above that of
the surrounding air for forty-eight hours; the
beer at the same time being very thick : at
the end of ninety-six hours the appearance
of the fermentation became more favour-
able ; the temperature of the beer sunk to
that of the surrounding air ; and the liquor
itself became somewhat clearer.
At this time its sp. gr. was 44.
IN the three following instances the pro-
cess of brewing was carried on in the com-
mon manner, and in the two first of them
99
by persons professionally ir* the habit of
brewing.
EXP*. xi.
In this process the operation of mashing
was applied three times to twenty bushels
of malt ground in the usual manner.
The capacity of the copper was four bar-
rels (144 gallons.)
The sp. gr. of the first wort was 195
of the second . . . 120
of the third ... 54
Part of the first and second worts were
boiled with ten pounds of hops : after
which the third wort and the remaining
part of the first and second were boiled
with the same hops.
The whole process occupied fifteen hours.
The sp. gr. of the mixture of the
three worts, after having been
boiled with the hops, was 135.
The quantity was 8 barrels
(288 gallons). It contained lb - < s".
therefore &c. . 152 8 119
40
which being the quantity ex-
tracted from 20 bushels, the
proportion in the quarter, or Ib - oz. grs.
8 bushels, is 61 46
EXP'. xn.
In this process the operation of mashing
was applied three times to twenty-eight
bushels of malt ground in the usual man-
ner.
Two coppers were employed : the capa-
city of one was nine barrels (324 gallons) ;
of the other, five barrels (180 gallons).
The sp. gr. of the first wort was .
of the second . . . 118
of the third ... 50
Part of the first and second worts was
boiled with twenty-one pounds of hops :
the third wort and the remaining part of
the first and second were then boiled with
the same hops.
41
The whole process occupied sixteen
hours.
The sp. gr. of the mixture of the three
worts, after having been boiled with the
hops, was 117-
The quantity was 12 barrels
(432 gallons). It contained lb - oz - g rs -
therefore &c 198 4 154
which being the amount of the
quantity obtained from 28
bushels, the proportion in the
quarter, or 8 bushels, is . 56 10 16.9
At the end of ninet3 r -six hours the sp. gr.
of this beer was 51.
EXP'. xin.
Twelve gallons of water, at the temp, of
170, were mashed for ten minutes with
9- of a bushel of malt: at the end. of an
hour and a half the wort was drawn off.
The sp. gr. of this wort wan
154. The quantity of it was 6
gallons. It contained there- ib. O z. g rs.
fore&e. ...'".*.. 3 9 408
Eight gallons of water, at the temp, of
170, were then added to the malt in the
mash-tun, and were mashed with it for ten
minutes : at the end of twelve hours the
wort was drawn off, and was at that time
of the temp, of 100.
The sp. gr. of this wort was 100.
The quantity was 6 gallons. Jb - *** s rs -
It contained therefore &c. . 2 5 270
A third wort, the sp. gr. of
which was 50, consisted of
4 gallons, and contained c. 12 236
The quantity in this case ex-
tracted from | of a bushel of
malt was ...... 6 12 39
The proportion therefore in the
quarter, or 8 bushels, is . 60 12 351
THE account of the foregoing experi-
ments has been collected from notes that
were accurately taken during the several
processes. Many more experiments have
been made on the plan of the first ten, and
apparently with similar success ; but, as the
management of them was committed in
a great measure to the care of others, the
similarity of the results can only be inferred
iti a general way.
In calculating the quantity of the seve-
ral worts very ample allowance was mad&
for the effect of expansion as depending
on temperature, and great care was taken
in weighing them ; so that the results here
given are certainly not above what they
ought to be: and in each of the experi-
ments, except the eleventh and twelfth,
both the quantity of the malt made use of
and of the wort obtained was measured by
single gallons. In all the calculations also,
44
also, as well of the* table as of the several
experiments, the same care was taken to
lessen rather than increase the estimates;
though it is believed that the error thus oc-
casioned, does not amount in any instance
to more than a few grains. In all those in-
stances where ^ of a bushel are stated to
have been used, it was originally intended
to use a bushel: the intention failed from
not having considered the difference in the
space occupied by equal weights of ground
and whole malt. In order to ascertain the
degree of this difference a Winchester bushel
was exactly filled with whole malt, which
was then put into a mill and ground in the
usual manner: it was received in a sack
placed under the mill, and afterwards mea~
* The calculations of the table were made on the supposi-
tion (as has been already stated) that the beer-pint of distilled
water weighs at 55 of Fahr'. 8924.41 875 grs; which number is
assumed from a statement, made on the authority of the late
Professor Robinson of Edinburgh, that a cubic inch of dis-
tilled water weighs, at 55 of Fahrt., 253. 175 grs.; wherefore,
as the capacity of the beer-pint is 35.25 cub. in., its weight
will be (253.175 x 35.25) 8924.41875 grs. Vid. Kerr's
Translation of Lavoisier's Elements of Chemistry. Edinb.
1796, 8vo. 3rd edit. Append, p. 585.
45
sured ; but instead of measuring 8 gal-
lons it measured g^J allowing therefore for
the occasional difference in the size of the
particles of different parcels of ground
malt, as resulting from the use of dif-
ferent mills, the increase in the bulk may
be taken generally as at least . Niae gal-
Ws of malt therefore ground in the com-
mon manner are equal to eight gallons, or a
Winchester bushel, of whole malt ; and as
in the foregoing instances only eight gallons
of the ground malt were used, the real
o
quantity of malt was $-of a bushel. When
malt is very finely ground the difference is
not quite so much : this difference was esti-
mated from a comparison of the different
weights of equal measures.
A gallon of malt ground in the Ib - z - g.
usual manner weighs . . 480
A gallon of finely ground malt
weighs ....... 4 11 260
The weight of 8 gallons of the
former is ....... 36
m
lb. oz. grs.
The weight &c. of the latter is 37 12 330
Ib. oz. grs. tb.
And since 37 12 330 : 36 :: 1 : 0.952453,
it follows that the result of each experiment
in which the finely ground malt was used
must be diminished in the proportion of
1 to 0.952453. The results therefore of the
five first experiments, when thus corrected,
will be
lb. oz. grs.
EXP. i. .
. 71 7 405
EXP. ir. .
. 71 5 359
EXP. in.
. 73 8 240
EXP. iv. .
. 65 78
EXP. v. .
65 13 233
The reason of using the malt so finely
ground arose from the observation that in
the common mode of grinding many grains
escape unbroken ; and it was found, by an
experiment made for the purpose, that the
water scarcely acts on these. The stirring
of the malt and hops with the water, first
mentioned in the fourth Experiment, was
found necessary to prevent the malt froni
burning to the bottom of the. copper : this
operation increases the trouble of the pro-
cess; but, where the malt is not finely
ground, it perhaps facilitates the extraction
of the saccharine matter.
In reviewing the foregoing experiments
it will be seen that the average of the five
first, after the correction made in pag. 46, is
69 Ib 7oz. 88grs.; and that in these in-
stances finely ground malt was used, and
the boiling heat was applied twice at
least.
In the five next Experiments the average
is 59 Ib. 128 grs. In these experiments
malt ground in the usual manner was
employed : in three out of the five indeed
the boiling heat was only applied once;
which circumstance may be supposed to
have contributed towards lessening the ave-
rage: but in the two instances where the
boiling heat was applied twice, the results
are not nearly so great as the average of
the results in the first five : so that the
diminution appears to depend more on
48
the state of the malt than on the degree of
O
heat applied.
In the three last Experiments lb - oz - s rs '
the average is 59 7 334
FROM the second Experiment it appears
that the addition of the soluble matter ex-
tracted from the hops is too trifling to deserve
notice ; for a wort, previously impregnated
with the saccharine matter &c. of the malt,
was only increased in sp.gr., after having been
boiled with the usual proportion of hops for
three quarters of an hour, from 118 to
118.5 : and in another instance, in which a
pound of hops was boiled for two hours
with fifteen gallons of water, the sp. gr. of
the water was only increased from 0.5 to 2,
or about 3 ounces in the barrel : but, were
the increase greater, it would be of no sig-
nification ; since in the common mode of
49
estimating the specific gravity of worts, the
estimate is taken after the addition of the
soluble matter of the hops.
It appears, from the first, third, ninth,
and thirteenth experiments, that a third
boiling, or even simple mashing, extracts an
additional quantity of saccharine matter
sufficient materially to affect the results:
wherefore the quantity obtained in the se-
cond, fourth, fifth, sixth,' and seventh expe-
riments would have been increased had the
operation of boiling or mashing been used a
third time, as it was in the other ex-
periments : so that the average given in
either instance is to be considered as less
than it might have been. But as the highest
average here given is below what profes-
sional persons have sometimes stated as the
average quantity of saccharine matter c.
to be expected from a quarter of malt, it
may be satisfactory to produce a statement
on this part of the subject from better au-
thority: the following is copied from a
* Publication, by a gentleman of the 'name
* York, 1805. 8vo. d edition, page 237.
H
50
of Richardson, entitled " The Philosophical
Principles of the Science of Brewing/*
Malt from the Barley of 1781.
Average Produce
No.
Colour.
Character.
Growth of Barley.
of Fermentable
Matter.
1
Pale.
Well made.
North Lincolnsh.
82 Pounds.
2
Ditto.
Indifferent.
Ditto.
75 Ditto.
3
Ditto.
Well made.
Norfolk.
72 Ditto,
4
Ditto.
Ditto.
YorkshireWoulds.
82 Ditto.
5
Brown.
Ditto.
Ditto.
78 Ditto,
6
Ditto.
Ditto.
Ware) in Herts.
56 Ditto,
Malt from the Barley of 1782,
No.
Colour.
Character.
1
Pale.
Well made.
2
Ditto.
Ditto.
3
Ditto.
Ditto.
4
Ditto.
Indifferent.
5
Brown.
Well made.
Growth of Barley.
YorkshireWoulds.
Bremen.
Norfolk.
Ditto.
Ware, in Herts.
Average Produce*
62 Pounds.
58 Ditto.
67 Ditto,
56 Ditto.
54 Ditto.
Malt from the Barley of 1783.
No.
Colour.
Character,
1
Pale.
Well made.
2
Ditto.
Ditto.
3
Ditto.
Indifferent.
4
Ditto.
Well made.
5
Brown.
Ditto.
Growth of Barley.
North Lincolnsh.
Berw k . on Tweed.
YorkshireWoulds.
Ditto.
Ditto.
Average Produce.
74 Pounds.
63 Ditto.
65 Ditto.
75 Ditto.
72 Ditto.
By this statement it appears that the
value of malt may be very different in dif-
51
ferent years ; for of the examples here
produced
lb, oz. grs.
The average for the year 1781 is 74 2 245
1782 59 6 175
1783 69,12 350
It is probable therefore, and it is believed
indeed to be the case, that the malt of the
present year is below the general average
value with respect to the proportion of its
saccharine contents. Should there howr
ever have been any error in the preceding
mode of calculation, which from its simpli-
city is not likely, it cannot affect the com-
parative value of the estimates; because
the same mode of calculation was adopted
in all the instances.
Upon the whole therefore it appears,
that the continued application of a boiling
heat to the malt certainly occasions no loss
with respect to the quantity of saccharine
matter extracted ; and that the use of finely
ground malt, instead of that which has
been ground in the usual manner, gives a
considerable additional profit. But the ad-
vantage of the method of Brewing here
recommended is more evident when the
consequent saving of time and labour is
considered ; in order to estimate which fair-
ly, it will be necessary to enter into a more
detailed comparison of the several stages of
the corftmon process, and of that recom-
mended in this Treatise.
In the instances of the eleventh and
twelfth experiments it is seen, that the
time occupied in brewing eight barrels
(the capacity of the copper being four
barrels) was fifteen hours; and the time
occupied in brewing twelve barrels (the
joint capacity of the two coppers being four-
teen barrels) was sixteen hours : but though
the processes were here conducted by per-
sons professionally in the habit of brewing,
and the whole apparatus was as well adapted
to the purpose as in a public brewery, yet
as profit was not the object of those at
whose expense the processes were carried
on, and therefore the saving of time was not
of much consequence, it might be consider-
ed hardly fair to use those instances as
examples in the following comparison : it is
53
presumed however, from the nature of the
process itself, that even in a public brewery
the proportion of time occupied cannot be
very different from that mentioned in the
first of those instances ; and that in this case
if the capacity of the copper were eight bar-
rels, and it were intended to brew sixteen
barrels of beer, the time necessary for the
process would be sixteen hours.
Suppose then with a copper of the same
size the same quantity of beer was to be
brewed by the method here recommended,
the several parts of the process with respect
to the time occupied would be as follows :
hours.
Filling and boiling the copper . . . ly
Boiling the first wort ...... Oj
Drawing off the first wort . . . . Q
Again filling and boiling the copper . *0f
Boiling the second wort 1
Drawing off the second wort . . .
* It would scarcely be so much ; because it has been found
by obser?ation that the heat of the malt in the copper raises
the temp, of the cold water to 150.
54
Mashing with a few gallons of cold
water for five minutes, and then
drawing off the third wort . . . . Ojr
i
Quantity of wort obtained eight barrels.
Allowing for the removal of the hours.
, malt and hops from the copper . 0^
Repeating the former process . . 4
4|
Quantity of wort obtained 8 barrels.
By the above two processes, sixteen bar-
rels of wort may be obtained in 9* hours ;
which is not much more than half the time
supposed to be employed in a public
brewery in obtaining the same quantity:
and the expense of and the room occupied
by a mash-tun are saved.
It remains to make a comparison of the
number of separate operations in the two
processes.
In the common process the following are
the operations necessarily employed.
55
Transferring the malt from the sack to
the mash-tun 1
Filling and boiling the copper ... 2
Transferring the hot water from the
copper to the mash-tun .... 3
Mashing ; and then transferring the
first wort from the mash-tun , . . 4
Again filling and boiling the copper . 5
Again transferring the hot water to the
mash-tun 6
Mashing ; and then transferring the se-
cond wort from the mash-tun , . . 7
Transferring water to the mash-tun for
the third mashing ,.,.. 8
Mashing; and then transferring the
third wort from the mash-tun. . . 9
Transferring to the copper, and boiling
together with the hops, a part of
the first and second worts ... 10
Transferring the wort thus boiled to
the cooler , 11
56,
Transferring &c. and boiling the third *
wort and remaining part of the first
and second 12
Transferring the wort thus boiled to
the cooler IS
In the process recommended in this Trea-
tise the necessary operations are
Transferring the malt and hops to the
copper . . . . 1
*.
Filling and boiling the copper ... 2
Drawing off the first wort into the
cooler .' .'.*....... 3
Again filling and boiling the copper . 4
Drawing t>ff the second wort into the
cooler , . . . 5
Adding a small proportion of cold
water, and mashing for five minutes . 6
Drawing off the third wort into the
cooler 7
So that the proportion of time and of
labour saved, by adopting the latter process,
is very nearly one half: the additional profit
arising from the use of finely ground malt
is common to both.
Having stated these advantages it is fair
to add that the plan is perhaps more calcu-
lated for domestic than for public Brew-
ing; at least it would require the experi-
ence of those who are conversant with the
subject to make it practicable on a large
scale. The objection to its application on
such a scale depends in some measure on
the space occupied by the malt and hops :
on which account, and also on account of
the proportion of water retained by the
malt, there cannot be drawn off from the
copper more than, indeed not quite so
much as, half the quantity of its capa-
city. Thus from a copper capable of
holding two barrels (seventy-two gallons),
since five bushels of malt and l^lb of hops
would occupy the space of about twenty gal-
lons of water, and each bushel would retain
about four gallons, not more than thirty-two
gallons would be recovered after each boiling.
In brewing table beer this objection is not
of much force, because the proportion of
malt used is comparatively small : a stronger
objection arises from the difficulty of keeping
a very large mass of malt in agitation during
i
58
the process of heating and boiling the water ;
though even this probably might be sur-
mounted by adapting to the copper the
apparatus which in large breweries is a-
dapted to the mash-tun.
It has already been stated that the beer
produced by the preceding method of brew-
ing is altogether not inferior to that which
has been brewed in the common way. Of
transparency and taste, the senses are suf-
ficiently accurate judges ; of its strength, or
the quantity of spirit of wine contained in
it, a tolerably correct estimate may be
formed by comparing the specific gravities
before and after fermentation.
In the publication above referred to, the
Author says (p. 187-) he has never known
the sp. gr. of malt liquor reduced more than
in the proportion of ~ of the sp. gr. of the
wort from which it was made ; in general
not more than in the proportion of f ; and
sometimes scarcely more than . There ap-
pears reason to conclude from another part
of the same publication, that the reduction
59
. is usually somewhat short of |-: forinp. 381.
there is this expression, " observing that a
"wort of 30 Ib per barrel was frequently
" attenuated to 10 lb;" which seems to im-
ply that the reduction was generally not
so much as two thirds. These data will
enable the reader to judge of the effect of
fermentation, as to this point, in the fore-
going experiments.
In the second experiment the
sp. gr. was reduced from 118.5
to 29 ; or in the proportion of . 0.76*
In the third &c. from 129 to 35 ;
or &c 0.73
In the fourth cScc. from 108 to 40 ;
or &c v . . 0.63
In the seventh &c. from 98 to 43 ;
or&c 0.57
In the eighth &c. from 110 to 43 ;
or &c 0.6i
In the ninth &c. from 108 to 48 ;
or&c. 0.56
In the tenth &c. from 115 to 37;
or&c 0.68
The average of these numbers is 0.6485
In three of the seven instances here men-
tioned the reduction of the sp. gr. was in
the proportion of above -f ; but even the
average is very nearly as high as y; and
when it is considered that the fermentation
had not proceeded in any instance beyond
the twenty -fourth, and on the whole not
beyond the sixteenth day, the results, as
compared with the statements just now
made, sufficiently prove that the fermenta-
tion of the beer here brewed produced the
usual proportion of spirit of wine.
A few observations have occurred on the
nature of fermentation, during the progress
of the experiments related in this Treatise ;
which, though not new perhaps to those
who have reflected scientifically on the sub-
ject, may yet be acceptable to others.
When } r east is mixed with wort at a pro-
per temperature, a froth is very soon formed
on the surface of the liquor ; consisting of
61
numerous air bubbles that are continually
rising from the bottom of the vessel in which
the process is carried on. At this time the
liquor is turbid and has scarcely any degree
of transparency; but as the process ad-
vances a gradual deposition of the opaque
particles takes place ; and the liquor be-
comes comparatively transparent, and spe-
cifically lighter : the change in the appear-
ance &c. is known to be accompanied with
the production of a quantity of spirit of wine
proportional to the quantity of saccharine
matter originally contained in the wort : and
hence beer which has been brewed from a
great proportion of malt is not only richer in
taste but more inebriating than beer which
has been brewed from a small proportion.
But as spirit of wine is specifically lighter
than even distilled water, and much more so
therefore than any wort, those opaque parti-
cles, which were easily suspended by the wort
before fermentation, now readily subside in
it; and the beer consequently becomes trans-
parent.
The transparency of beer is sometimes
promoted by means of isinglass, or similar
substances, technically known by the name of
" Finings ;" the action of all of which is merely
mechanical, and only produces transparency
without adding in the least to the strength
of the beer ; no injury however is done to
the beer by this means, and in commerce the
practice is in a great measure necessary for
the purpose of a quick sale. But for domes-
tic purposes this is scarcely of any conse-
quence; for, if the fermentation has been car-
ried on properly, the beer will be in a few
weeks as clear as is in general required, even
though the proportion of the malt emplo} r ed
in brewing it should not have been more than
two bushels to the barrel : the same degree
of transparency may indeed be acquired in
a few days by producing fermentation at a
high temperature. The full range of tem-
perature as applicable to the process of fer-
mentation is not any where accurately de-
fined : it is generally however understood that
it proceeds in a languid manner at a tem-
perature lower than 50; and that the ra-
pidity of it increases with increased tem-
peraturq. In one instance, it commenced
63
very favourably at a temp, as high as 108 ;
and the liquor being then exposed to a
temp, of about 60, fermentation went on in
the usual manner, and the beer was very
transparent in two days. The rapidity of
fermentation depends also in part upon the
quantity of yeast employed *.
The extrication of air during the process
of fermentation and the consequent diminu-
tion in sp. gr. and increased transparency of
the liquor are obvious under common cir-
cumstances : in order to ascertain more ac-
curately the nature of these phenomena the
following method was emploj^ed.
A quart bottle of perfectly transparent
and colourless flint-glass was completely
filled with some wort, to which yeast had
* Wort, unless it contains a very small proportion of sac.
charine matter, will ferment without the addition of any yeast.
In one instance two quarts of yeast were added to 3| gallons
of wort, in a small barrel, at the temp, of 80 : fermentation
commenced within two minutes after the addition of the yeast;
and for half an hour a froth continued to rise from the mouth
of the barrel as rapidly as when a bottle of fermented liquor
that has been kept long corked is suddenly opened.
64
been just added ; *t was then immediately
stopped with a cork, through which a small
bent glass tube had been previously passed :
the cork being then cemented accurately
with melted wax the only communication
between the outer air and the inside of the
bottle was by means of the tube ; the end of
which being immersed under water none of
the external air could find admission, while
any air that should be extricated from the
liquor, as it must ultimately pass out at that
end of the tube which was immersed
under water, could easily be received in
a vessel inverted over the aperture of the
tube. v
This description of the common pneu-
matic apparatus is inserted for the conve-
nience of those who haVe not been in the
habit of making chemical experiments;
and will therefore be excused by those to
whom the apparatus itself is familiar.
It would be tedious and beyond the pur-
pose of this treatise to detail all the minute
circumstances of the experiments to which
65
the foregoing apparatus was applied : it is
sufficient for the present to say that in that
apparatus the process of fermentation was
repeated several times ; and the phenomena
of the several experiments corresponded
sufficiently closely with each other to justify
the following general description *.
In a few minutes a sediment is deposited
consisting of the yeast and of the heavier
opaque particles of the wort : immediately
after which a number of minute bubbles of
air are disengaged from every part of the
surface of the sediment ; and many of these
carry up with themselves detached particles
of the yeast : some of these particles sink
again by their own weight ; others adhering
to the edge of the glass remain fixed, and
successive particles are gradually attached
to them till at length the whole surface of
the liquor is covered -f-.
* In most of the experiments the fermentation was produced
, at a high temperature, and the phenomena therefore succeeded
each other more quickly than they would otherwise have done.
t This forms what is called the " head " of the beer ;
which by many is mixed again wifh the fermenting liquor
K
In proportion as these bubbles are dis-
engaged the colour of the sediment becomes
lighter, the change commencing at the sur-
face and penetrating further as the process
advances ; from which circumstance it ap-
pears evident that the production of the air
is connected with this change in colour : and
from the loss of weight in the fermenting
mass it is probable that this change of colour
is attended with a loss of substance : the
air extricated during fermentation is that
which is called Fixed Air, and which is
known to possess acid properties.
Those who are prepared to think scienti-
fically on the subject will perhaps be clis-
Iwo or three times during the fermentation ; and as this head
consists,, of those very particles from which fermentation pro-
ceeds, the reason of this practice is apparent. It seems how-
ever extraordinary, considering the close connexion between
the proportion of saccharine matter held in solution in the
wort and of spirit of wine produced by fermentation, that
these bubbles should not be seen originating from every part
of the fermenting mass. The probability is that they are
extricated from every part, but that from circumstances with
which we are at present unacquainted they cannot be readily
seei).
67
posed to allow that the substance apparently
separated from the sediment of the ferment-
ing mass becomes one of the constituent
parts of the air which is at the same time
extricated; and that the other constituent
part of that air, on which its acid character
depends, has been afforded by the decom-
position of the water. If this supposition
be true, the connexion between the dimi-
nution of the saccharine matter and the
presence of the spirit of wine is easily ex-
plained.
In three instances it was found that the
weight of air produced very nearly corres-
ponded with the loss of weight in the liquor ;
and that at least 75- of the volume of the air
produced was of that kind called Fixed Air.
These are the principal remarks which
have occurred on the nature of fermentation
in the course of the foregoing experiments ;
and the author hopes to find opportunities
of pursuing them further : in which case the
results, should they be thought of sufficient
68
consequence, will be published : but he
rather hopes that others who have more lei-
sure than himself will direct their attention
towards the investigation of this subject,
and throw some light on a branch of Che-
mistry as yet but very imperfectly under-
stood.
THE END.
ERRATA.
Pag. 18. 1. 3. from the bottom, for 2600 to 2600.3
read 2600.5 to 2600.
Pag. 19. I. 16. for 35.5 read 35.85,
Printed by Nathaniel Bliss, Oxford.
J /? - I "
c.> (
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